This is a book worth reading, regardless of whether you're sympathetic to Greer's point of view or not. I found myself agreeing with the thrust of Greer's argument, though I had minor quibbles with a few of his points and I think his timeline for the decline of industrial civilization is too early and fails to take into account how proven reserves of oil, gas, and other natural resources are accounted for.
The main weakness of this work is Greer's tendency to make arguments that appeal to the biases of the majority of his readers. He routinely puts down politicians and industrialized processes like fracking with a snide comment, and though these are often justified and correct, he doesn't provide any evidence for them other than his own claims. This weakens his argument and gives his critics something to latch on to. Nonetheless, The Retro Future is worth engaging with and reflecting on. I found it caused me to rethink some of my lifestyle choices and I intend to change some of the ways I spend my time and energy as a result.